This research program will develop a new membrane which has as a desirable property of enhanced permeation to charged peptides, such as gastrin releasing peptide, GRP-10, thus permitting a higher permeation and a longer lifetime of the membrane in the stomach environment than has been heretofore possible. This membrane is to be produced by the use of a suitable substrate, such as polysulfone, designed to a specified size to enhance permeation of bulky proteins. Subsequent (plasma) protonation of the membrane provides for a change in the chemical characteristics of the membrane which allows enhanced permeation of the membrane to highly polar Species.